Today, January 9th, is the date of the final battle of the California Campaign of the Mexican-American War. The Battle of La Mesa occurred one day after the Battle of Rio San Gabriel and brought an end to hostilities between American forces and the Californios.
The site of the battle was on a plain between the Los Angeles River and the San Gabriel River. The city of Vernon, just south of downtown Los Angeles, now occupies the site.
The two sides looked to be evenly matched: 300 Mexican Californians under Jose Maria Flores faced 300 American troops under Commodore Robert Stockton and General Stephen Watts Kearny. But the Americans were armed with rifles, while the Californios were armed only with lances.
Marching toward Los Angeles, the American troops encountered the Californios on horseback, who extended their line to surround the Americans. The cavalry charged the American troops, but were cut down by relentless rifle fire and forced to retreat. Losses during this and the precious day’s battle consisted of three dead on each side and several wounded.
The conquest of California was settled with the signing of the Treaty of Cahuenga by Lieutenant-Colonel John C. Frémont and Californio General Andrés Pico four days later, on January 13, 1847.